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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, James Holderness <j4_james@hotmail.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH 4.15 082/105] tty: vt: fix up tabstops properly
Date:   Tue, 27 Mar 2018 18:28:02 +0200
Message-Id: <20180327162803.352968439@linuxfoundation.org>
In-Reply-To: <20180327162757.813009222@linuxfoundation.org>
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4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Linus Torvalds <torvalds@linux-foundation.org>

commit f1869a890cdedb92a3fab969db5d0fd982850273 upstream.

Tabs on a console with long lines do not wrap properly, so correctly
account for the line length when computing the tab placement location.

Reported-by: James Holderness <j4_james@hotmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/tty/vt/vt.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -1727,7 +1727,7 @@ static void reset_terminal(struct vc_dat
 	default_attr(vc);
 	update_attr(vc);
 
-	vc->vc_tab_stop[0]	= 0x01010100;
+	vc->vc_tab_stop[0]	=
 	vc->vc_tab_stop[1]	=
 	vc->vc_tab_stop[2]	=
 	vc->vc_tab_stop[3]	=
@@ -1771,7 +1771,7 @@ static void do_con_trol(struct tty_struc
 		vc->vc_pos -= (vc->vc_x << 1);
 		while (vc->vc_x < vc->vc_cols - 1) {
 			vc->vc_x++;
-			if (vc->vc_tab_stop[vc->vc_x >> 5] & (1 << (vc->vc_x & 31)))
+			if (vc->vc_tab_stop[7 & (vc->vc_x >> 5)] & (1 << (vc->vc_x & 31)))
 				break;
 		}
 		vc->vc_pos += (vc->vc_x << 1);
@@ -1831,7 +1831,7 @@ static void do_con_trol(struct tty_struc
 			lf(vc);
 			return;
 		case 'H':
-			vc->vc_tab_stop[vc->vc_x >> 5] |= (1 << (vc->vc_x & 31));
+			vc->vc_tab_stop[7 & (vc->vc_x >> 5)] |= (1 << (vc->vc_x & 31));
 			return;
 		case 'Z':
 			respond_ID(tty);
@@ -2024,7 +2024,7 @@ static void do_con_trol(struct tty_struc
 			return;
 		case 'g':
 			if (!vc->vc_par[0])
-				vc->vc_tab_stop[vc->vc_x >> 5] &= ~(1 << (vc->vc_x & 31));
+				vc->vc_tab_stop[7 & (vc->vc_x >> 5)] &= ~(1 << (vc->vc_x & 31));
 			else if (vc->vc_par[0] == 3) {
 				vc->vc_tab_stop[0] =
 					vc->vc_tab_stop[1] =